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Abstract:

An exhaust gas recirculation device for an internal combustion engine
includes a return line, which branches off an exhaust tract and leads
into an intake tract. A separator component is arranged in the return
line. Downstream of the separator component, a gas line, via which
additional gas can be supplied, leads into the return line.

Claims:

1. An exhaust gas recirculation device for an internal combustion engine
(1), comprising a return line (11) that branches off an exhaust gas
manifold (4) of the internal combustion engine (1) and opens into an
intake manifold (6) of the internal combustion engine (1), comprising a
separator component (14) arranged in the return line (11), wherein
upstream of the separator component (14) a gas line (15) opens into the
return line (11), wherein by means of the gas line (15) additional gas,
in particular air, can be supplied.

2. Exhaust gas recirculation device according to claim 1, wherein an
adjustable control valve (16) is arranged in the gas line (15).

3. Exhaust gas recirculation device according to claim 1, wherein in the
return line (11) a mixer component (17) is arranged into which the gas
line (15) opens.

4. Exhaust gas recirculation device according to claim 1, wherein the
separator component is embodied as a cyclone separator (14).

5. Exhaust gas recirculation device according to claim 1, wherein in the
return line (11) an exhaust gas cooler (13) is arranged upstream of the
separator component (14).

7. An internal combustion engine with an exhaust gas recirculation device
(10) according to claim 1.

8. Internal combustion engine according to claim 7, wherein the internal
combustion engine (1) is provided with an exhaust gas turbocharger (2)
with a compressor (5), wherein the return line (11) branches off the
exhaust gas manifold (4) downstream of an exhaust gas turbine (3) and
opens upstream of the compressor (5) into the intake manifold (6).

9. Internal combustion engine according to claim 7, wherein the gas line
(15) branches off downstream of an air filter (9) in the intake manifold
(6).

10. Internal combustion engine according to claim 7, wherein by means of
the gas line (15) additional gas is to be introduced into the return line
(11), separate from the intake manifold (6).

11. A method for operating an exhaust gas recirculation device (10) of
claim 8 for an internal combustion engine (1), comprising: controlling
mass air flow supplied by the gas line (15) as a function of the actual
load state or the engine speed of the internal combustion engine (1).

12. The method according to claim 11, wherein in the controlling step,
mass air flow is controlled such that the air mass flow to be supplied is
reduced at low loads or engine speeds and is increased at higher loads or
engine speeds.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is U.S. bypass continuation of international
patent application no. PCT/EP2012/051089, filed Jan. 25, 2012 designating
the United States of America, the entire disclosure of which is
incorporated herein by reference. PCT/EP2012/051089 claims priority to
German patent application no. 10 2011 009 916.6, filed Jan. 31, 2011.

[0003] EP 2 199 585 A1 discloses a charged internal combustion engine that
is provided with an exhaust gas recirculation device. The exhaust gas
recirculation device comprises a return line that is branching off
downstream of an exhaust gas purification unit in the exhaust gas
manifold of the internal combustion engine and opens into the intake
manifold upstream of a compressor which is a component of an exhaust gas
turbo charger. The exhaust gas turbine of the exhaust gas turbocharger is
arranged upstream of the exhaust gas purification unit in the exhaust gas
manifold.

[0004] In the return line an adjustable valve and as well as an exhaust
gas cooling device are arranged by means of which the exhaust gas is
cooled to lower temperatures before being introduced into the intake
manifold. Moreover, in the return line a cyclone separator is arranged by
means of which particles are separated which are entrained in the gas
flow through the return line. Such particles, originating for example
from the exhaust gas purification unit, can cause damage of the motor as
well as of the exhaust gas turbocharger.

[0005] The invention has the object to separate with simple measures and
in an efficient way particles from the gas flow that is being passed
through an exhaust gas recirculation device of an internal combustion
engine.

SUMMARY OF THE INVENTION

[0006] The exhaust gas circulation device according to the invention is
used in internal combustion engines and serves for returning a portion of
the exhaust gas flow from the exhaust gas manifold of the internal
combustion engine into the intake manifold in order to improve the
exhaust gas behavior and consumption behavior of the internal combustion
engine.

[0007] In a return line of the exhaust gas recirculation device there is a
separator component which serves to separate particles that are entrained
with the exhaust gas flow through the return line in order to prevent
damage to the internal combustion engine or other components correlated
with the internal combustion engine. The entrained particles are enlarged
by a so-called heterogeneous condensation in that, by a drop below the
dew point, water droplets will aggregate by condensation on the particles
so that as a whole the particles have a greater mass and the efficiency
of separation is improved by higher inertia forces.

[0008] According to the invention, upstream of the separator component a
gas line though which additional gas can be supplied opens into the
return line. The additional gas is preferably air wherein optionally also
another gas can be supplied, for example, additional exhaust gas.

[0009] By means of supply of the additional gas, which has a lower
temperature than the recirculated exhaust gas flow through the return
line, a lower temperature is achieved overall by admixture of the
recirculated exhaust gas so that a drop below the dew point is more
easily achieved and the condensation is improved. Inasmuch as air is
supplied through the gas line, an additional adjustable parameter for
controlling the exhaust gas concentration is available also.

[0010] Moreover, an improved adaptation to different operating conditions
of the internal combustion engine is possible. Depending on the actual
operating state of the internal combustion engine, the quantity of the
supplied gas proportion into the return line can be adjusted. For
regulating the quantity, an adjustable control valve is expediently
provided that is arranged in the gas line.

[0011] Mixing of the recirculated gas mass flow with the exhaust gas mass
flow that is guided through the return line is realized preferably by
means of a mixing component that is integrated into the return line. The
gas line opens into the mixing component for mixing the gas proportion
with the exhaust gas.

[0012] According to an advantageous embodiment, it is provided that the
separator component is a cyclone separator. Such cyclone separators are
characterized by a constructively simple and efficient configuration and
can be installed even within a small mounting space. In the cyclone
separator the separation of the particles that have been enlarged by
condensed liquid is realized as a result of increased inertia forces.

[0013] In one embodiment, the separator component is arranged downstream
of the mixing component. In a further embodiment, the mixing component is
a mixing chamber that is integrated into the cyclone separator wherein in
particular the separating section of the cyclone separator can be
downstream of the mixing chamber in the flow direction.

[0014] The exhaust gas recirculation device comprises advantageously a
controllable recirculation valve as well as an exhaust gas cooler that is
integrated into the return line. By means of the recirculation valve the
quantity of the exhaust gas mass flow through the return line can be
adjusted. In the exhaust gas cooler, which is arranged upstream of the
separator component as well as of the opening location of the gas line
into the return line, the exhaust gas is cooled that is branched off the
exhaust gas manifold and is at high temperature.

[0015] The internal combustion engine in which the exhaust gas
recirculation device is used can be provided with an exhaust gas
turbocharger which comprises a compressor in the intake manifold and an
exhaust gas turbine in the exhaust gas manifold. In case of a diesel
internal combustion engine, a diesel particulate filter, by means of
which the soot particles in the exhaust gas are separated, is arranged
downstream of the exhaust gas turbine in the exhaust gas manifold. The
return line branches off downstream of the exhaust gas turbine and, in
case of the diesel particulate filter, downstream of the latter.
Particles which will detach from the exhaust gas purification unit
usually configured as a particle filter and which pass into the return
line are separated as described above in the separator component. In case
of a diesel particulate filter, the latter comprises for example a
ceramic body wherein, by means of the separator unit, it is prevented
that accidentally detached ceramic particles can pass into a possibly
present compressor and into the internal combustion engine.

[0016] The gas line that is opening into the return line branches off
advantageously downstream of an air filter in the intake manifold.
However, possible is also an embodiment in which by means of a gas line,
separate from the intake manifold, additional gas, in particular ambient
air, is to be supplied into the return line wherein optionally an
additional air filter is integrated into the gas line.

[0017] In a further embodiment, a pumping device is provided in the gas
line that opens into the return line and conveys the air from the intake
manifold or, alternatively, from the environment into the exhaust gas
return line. The pumping device can operate with uniform performance or
can be controlled by means of an operating map.

[0018] In a further embodiment, a throttling device is provided in the
intake manifold between the outflow location for the gas line and the
inflow location for the return line of the exhaust gas recirculation
device into the intake manifold in order to enhance the pressure drop
between the intake manifold and exhaust gas recirculation device or
between outflow location and inflow location at the intake manifold. The
throttle device can be adjusted to a constant value or can be variably
controlled according to a predetermined operating map.

[0019] In a method for operating the exhaust gas circulation device for an
internal combustion engine, it is provided that the air mass flow that is
to be supplied through the gas line is dependent on the actual load state
and/or the engine speed of the internal combustion engine. It is
particularly expedient to reduce, optionally down to zero, at low loads
or low engine speeds the air mass flow to be supplied or another gas mass
flow that passes through the gas line into the return line and to
increase it at higher loads or higher engine speeds because in these
operating states the cooling action of the recirculated exhaust mass flow
by means of the exhaust gas cooler is possibly insufficient for
generating a drop below the dew point.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further advantages and expedient embodiments can be taken from the
additional claims, the FIGURE description, and the drawing in which
schematically an internal combustion engine with exhaust gas turbocharger
and exhaust gas recirculation device is illustrated.

DETAILED DESCRIPTION

[0021] The internal combustion engine 1 illustrated in the FIGURE is
provided with an exhaust gas turbocharger 2 that comprise an exhaust gas
turbine 3 in the exhaust gas manifold 4 and a compressor 5 in the intake
manifold 6. The exhaust gas turbine 3 is driven by the pressurized
exhaust gases of the internal combustion engine 1 wherein a compressor
wheel in the compressor 5 is driven by means of a connecting shaft by the
turbine wheel in the exhaust gas turbine 3 and the supplied combustion
air in the intake manifold 6 is compressed to an increased charge
pressure at which the combustion air is supplied to the cylinders of the
internal combustion engine 1. In the intake manifold 6 an air filter 9 is
arranged upstream of the compressor 5.

[0022] In the exhaust gas manifold 4 downstream of the exhaust gas turbine
3 a ceramic particle filter 7 is arranged by means of which soot
particles entrained in the exhaust gas are separated. Moreover,
downstream of the particle filter 7 in the exhaust gas manifold 4 an
exhaust gas aftertreatment unit 8 is arranged.

[0023] Moreover, the internal combustion engine 1 is provided with an
exhaust gas recirculation device 10 by means of which a partial mass flow
of the exhaust gas is recirculated from the exhaust gas manifold 4 into
the intake manifold 6. This is done in certain operating states of the
internal combustion engine in order to improve the consumption behavior
and exhaust gas behavior of the internal combustion engine.

[0024] The exhaust gas recirculation device 10 comprises a return line 11
that branches off downstream of the particle filter 7 from the exhaust
gas manifold 4 and opens between the air filter 9 and the compressor 5
into the intake manifold 6. In the return line 11 there is an adjustable
recirculation valve 12 as well as an exhaust gas cooler 13 by means of
which the recirculated exhaust gas mass flow is cooled to lower
temperatures. Moreover, downstream of the exhaust gas cooler 13 a cyclone
separator 14 is integrated into the return line 11 wherein by means of
the cyclone separator 14 particles that are entrained in the exhaust gas
mass flow are separated. This is done by the inertia forces of the
particles causing the latter to deposit in the cyclone separator 14 while
the exhaust gas is further conveyed through the clean air outlet 18 of
the cyclone separator 14 into the intake manifold 6. For improving the
degree of separation, a condensation of moisture on the dirt particles in
the recirculated exhaust gas mass flow downstream of the gas cooler 13
takes place. In this way, the particles are imparted with a considerably
higher weight, which improves the separation in the cyclone separator.

[0025] For a further improvement of the efficiency of separation, a gas
line 15 is provided which is branching off the intake manifold downstream
of the air filter 9 but upstream of the opening location of the return
line 11 into the intake manifold 6 and opens into a mixing unit 17 that
is located in the return line 11 between the exhaust gas cooler 13 and
the cyclone separator 14. Sucked-in ambient air that is filtered in the
air filter 9 is returned through the gas line 15 from the intake manifold
6 and is passed in the area of the mixing unit 17 into the return line 11
and is mixed therein with the recirculated exhaust gas mass flow.
Accordingly, the temperature of the exhaust gas will drop further so that
in further operating areas a drop below the dew point may occur and a
better condensation of moisture on the particles in the exhaust gas mass
flow is achieved. As a result, the degree of separation in the cyclone
separator 14 is improved also.

[0026] In the gas line 15 an adjustable control valve 16 is arranged in
order to adjust the air mass flow through the gas line 15. It is in
particular provided to set the proportion of the air mass flow through
the gas line 15 as a function of the actual operating state of the
internal combustion engine. The recirculated gas mass flow depends
advantageously on the actual load state and/or the engine speed of the
internal combustion engine, preferably in such a way that at low loads or
engine speeds the air mass flow through the gas line 15 is reduced,
optionally down to zero, and is increased at higher loads or engine
speeds.

[0027] According to an alternative embodiment, illustrated in dashed line,
the gas line 15 is embodied as a separate line that does not branch off
the intake manifold but through which additional gas, in particular
ambient air, is to be supplied to the return line wherein optionally an
additional air filter 19 is integrated into the gas line 15.